func (i *Sniffer) decodePackets() {
	var eth layers.Ethernet
	var ip layers.IPv4
	var tcp layers.TCP
	var payload gopacket.Payload

	parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet, &eth, &ip, &tcp, &payload)
	decoded := make([]gopacket.LayerType, 0, 4)

	for {
		select {
		case <-i.stopDecodeChan:
			return
		case timedRawPacket := <-i.decodePacketChan:
			newPayload := new(gopacket.Payload)
			payload = *newPayload
			err := parser.DecodeLayers(timedRawPacket.RawPacket, &decoded)
			if err != nil {
				continue
			}
			flow := types.NewTcpIpFlowFromFlows(ip.NetworkFlow(), tcp.TransportFlow())
			packetManifest := types.PacketManifest{
				Timestamp: timedRawPacket.Timestamp,
				Flow:      flow,
				RawPacket: timedRawPacket.RawPacket,
				IP:        ip,
				TCP:       tcp,
				Payload:   payload,
			}
			i.dispatcher.ReceivePacket(&packetManifest)
		}
	}
}

func makeTestPacket() []byte {
	var testSeq uint32 = 12345
	buf := gopacket.NewSerializeBuffer()
	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}
	eth := layers.Ethernet{
		SrcMAC: net.HardwareAddr{0xde, 0xad, 0xbe, 0xee, 0xee, 0xff},
		DstMAC: net.HardwareAddr{0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
	}
	ip := layers.IPv4{
		SrcIP:    net.IP{1, 2, 3, 4},
		DstIP:    net.IP{2, 3, 4, 5},
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SYN:       true,
		SrcPort:   1,
		DstPort:   2,
		Seq:       testSeq,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3}},
	}
	tcp.SetNetworkLayerForChecksum(&ip)
	gopacket.SerializeLayers(buf, opts, &eth, &ip, &tcp)
	packetData := buf.Bytes()
	return packetData
}

// getPacketFlow returns a TcpIpFlow struct given a byte array packet
func NewTcpIpFlowFromPacket(packet []byte) (*TcpIpFlow, error) {
	var ip layers.IPv4
	var tcp layers.TCP
	decoded := []gopacket.LayerType{}
	parser := gopacket.NewDecodingLayerParser(layers.LayerTypeIPv4, &ip, &tcp)
	err := parser.DecodeLayers(packet, &decoded)
	if err != nil {
		return &TcpIpFlow{}, err
	}
	return &TcpIpFlow{
		ipFlow:  ip.NetworkFlow(),
		tcpFlow: tcp.TransportFlow(),
	}, nil
}

func BenchmarkMultiStreamGrow(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		Seq:       0,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		t.SrcPort = layers.TCPPort(i)
		a.Assemble(netFlow, &t)
		t.Seq += 10
	}
}

func BenchmarkSingleStreamLoss(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		SYN:       true,
		Seq:       1000,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		a.Assemble(netFlow, &t)
		t.SYN = false
		t.Seq += 11
	}
}

func TestGetOverlapRingsWithZeroRings(t *testing.T) {
	ip := layers.IPv4{
		SrcIP:    net.IP{1, 2, 3, 4},
		DstIP:    net.IP{2, 3, 4, 5},
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SYN:     true,
		SrcPort: 1,
		DstPort: 2,
	}
	tcp.SetNetworkLayerForChecksum(&ip)
	payload := gopacket.Payload([]byte{1, 2, 3, 4})
	p := types.PacketManifest{
		IP:      ip,
		TCP:     tcp,
		Payload: payload,
	}
	options := ConnectionOptions{
		MaxBufferedPagesTotal:         0,
		MaxBufferedPagesPerConnection: 0,
		MaxRingPackets:                40,
		PageCache:                     nil,
		LogDir:                        "fake-log-dir",
	}

	f := &DefaultConnFactory{}
	conn := f.Build(options).(*Connection)

	ipFlow, _ := gopacket.FlowFromEndpoints(layers.NewIPEndpoint(net.IPv4(1, 2, 3, 4)), layers.NewIPEndpoint(net.IPv4(2, 3, 4, 5)))
	tcpFlow, _ := gopacket.FlowFromEndpoints(layers.NewTCPPortEndpoint(layers.TCPPort(1)), layers.NewTCPPortEndpoint(layers.TCPPort(2)))
	serverFlow := types.NewTcpIpFlowFromFlows(ipFlow, tcpFlow)
	clientFlow := serverFlow.Reverse()
	conn.serverFlow = serverFlow
	conn.clientFlow = clientFlow

	head, tail := getOverlapRings(&p, serverFlow, conn.ClientStreamRing)
	if head == nil || tail == nil {
		return
	} else {
		t.Fail()
	}
	return
}

func sendPacket(handle *pcap.Handle, sMac, dMac net.HardwareAddr, sIp, dIp net.IP, sPort, dPort layers.TCPPort, IpId uint16, IpTtl uint8, TcpSeq, ack uint32, WindowsSize uint16, data []byte) error {
	eth := layers.Ethernet{
		SrcMAC:       sMac,
		DstMAC:       dMac,
		EthernetType: layers.EthernetTypeIPv4,
	}
	ip4 := layers.IPv4{
		SrcIP:    sIp,
		DstIP:    dIp,
		Id:       IpId,
		Flags:    layers.IPv4DontFragment,
		Version:  4,
		TTL:      IpTtl,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SrcPort: sPort,
		DstPort: dPort,
		Seq:     TcpSeq,
		ACK:     true,
		Ack:     ack,
		Window:  WindowsSize,
		PSH:     true, // 立刻处理
	}

	if len(data) == 0 {
		tcp.RST = true
	}

	tcp.SetNetworkLayerForChecksum(&ip4)

	buf := gopacket.NewSerializeBuffer()
	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}

	payload := gopacket.Payload(data)

	if err := gopacket.SerializeLayers(buf, opts, &eth, &ip4, &tcp, payload); err != nil {
		return err
	}

	return handle.WritePacketData(buf.Bytes())
}

func BenchmarkMultiStreamConn(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		Seq:       0,
		SYN:       true,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		t.SrcPort = layers.TCPPort(i)
		a.Assemble(netFlow, &t)
		if i%65536 == 65535 {
			if t.SYN {
				t.SYN = false
				t.Seq += 1
			}
			t.Seq += 10
		}
	}
}

func TestNewTcpIpFlowFromPacket(t *testing.T) {
	buf := gopacket.NewSerializeBuffer()
	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}
	ip := layers.IPv4{
		SrcIP:    net.IP{1, 2, 3, 4},
		DstIP:    net.IP{2, 3, 4, 5},
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SYN:       true,
		SrcPort:   1,
		DstPort:   2,
		Seq:       123,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3}},
	}
	tcp.SetNetworkLayerForChecksum(&ip)
	gopacket.SerializeLayers(buf, opts, &ip, &tcp)
	packetData := buf.Bytes()
	flow1, err := NewTcpIpFlowFromPacket(packetData)

	ipFlow2, _ := gopacket.FlowFromEndpoints(layers.NewIPEndpoint(net.IPv4(1, 2, 3, 4)), layers.NewIPEndpoint(net.IPv4(2, 3, 4, 5)))
	tcpFlow2, _ := gopacket.FlowFromEndpoints(layers.NewTCPPortEndpoint(layers.TCPPort(1)), layers.NewTCPPortEndpoint(layers.TCPPort(2)))
	flow2 := NewTcpIpFlowFromFlows(ipFlow2, tcpFlow2)

	if err != nil && !flow2.Equal(flow1) {
		t.Error("NewTcpIpFlowFromPacket fail")
		t.Fail()
	}

	flow1, err = NewTcpIpFlowFromPacket([]byte{1, 2, 3, 4, 5, 6, 7})
	if err == nil || !flow1.Equal(&TcpIpFlow{}) {
		t.Error("NewTcpIpFlowFromPacket fail")
		t.Fail()
	}
}

func BenchmarkSingleStreamSkips(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		SYN:       true,
		Seq:       1000,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	skipped := false
	for i := 0; i < b.N; i++ {
		if i%10 == 9 {
			t.Seq += 10
			skipped = true
		} else if skipped {
			t.Seq -= 20
		}
		a.Assemble(netFlow, &t)
		if t.SYN {
			t.SYN = false
			t.Seq++
		}
		t.Seq += 10
		if skipped {
			t.Seq += 10
			skipped = false
		}
	}
}

func TestSequenceFromPacket(t *testing.T) {
	var testSeq uint32 = 12345
	buf := gopacket.NewSerializeBuffer()
	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}
	ip := layers.IPv4{
		SrcIP:    net.IP{1, 2, 3, 4},
		DstIP:    net.IP{2, 3, 4, 5},
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SYN:       true,
		SrcPort:   1,
		DstPort:   2,
		Seq:       testSeq,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3}},
	}
	tcp.SetNetworkLayerForChecksum(&ip)
	gopacket.SerializeLayers(buf, opts, &ip, &tcp)
	packetData := buf.Bytes()
	seq, err := SequenceFromPacket(packetData)
	if err != nil && seq != testSeq {
		t.Error("SequenceFromPacket failed")
		t.Fail()
	}

	seq, err = SequenceFromPacket([]byte{1, 2, 3})
	if err == nil {
		t.Error("SequenceFromPacket should have failed")
		t.Fail()
	}
}

func (r *RawSocketServer) injectPacketFromDst(tcpLayer *layers.TCP, rawBytes []byte) error {
	// Preparing ipLayer.
	ipLayer := &layers.IPv4{
		SrcIP:    r.dst.ip,
		DstIP:    r.src.ip,
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}

	options := gopacket.SerializeOptions{
		ComputeChecksums: true,
		FixLengths:       true,
	}

	tcpLayer.SrcPort = r.dst.port
	tcpLayer.DstPort = r.src.port
	tcpLayer.Window = r.window

	tcpLayer.Ack = r.ack
	tcpLayer.Seq = r.seq

	tcpLayer.SetNetworkLayerForChecksum(ipLayer)

	// And create the packet with the layers
	buffer := gopacket.NewSerializeBuffer()
	gopacket.SerializeLayers(buffer, options,
		ipLayer,
		tcpLayer,
		gopacket.Payload(rawBytes),
	)

	outgoingPacket := buffer.Bytes()

	p := tuntap.Packet{
		Protocol:  0x800,
		Truncated: false,
		Packet:    outgoingPacket,
	}

	return r.iface.WritePacket(&p)
}

func main() {
	defer util.Run()()
	var handle *pcap.Handle
	var err error
	if *fname != "" {
		if handle, err = pcap.OpenOffline(*fname); err != nil {
			log.Fatal("PCAP OpenOffline error:", err)
		}
	} else {
		// This is a little complicated because we want to allow all possible options
		// for creating the packet capture handle... instead of all this you can
		// just call pcap.OpenLive if you want a simple handle.
		inactive, err := pcap.NewInactiveHandle(*iface)
		if err != nil {
			log.Fatal("could not create: %v", err)
		}
		defer inactive.CleanUp()
		if err = inactive.SetSnapLen(*snaplen); err != nil {
			log.Fatal("could not set snap length: %v", err)
		} else if err = inactive.SetPromisc(*promisc); err != nil {
			log.Fatal("could not set promisc mode: %v", err)
		} else if err = inactive.SetTimeout(time.Second); err != nil {
			log.Fatal("could not set timeout: %v", err)
		}
		if *tstype != "" {
			if t, err := pcap.TimestampSourceFromString(*tstype); err != nil {
				log.Fatalf("Supported timestamp types: %v", inactive.SupportedTimestamps())
			} else if err := inactive.SetTimestampSource(t); err != nil {
				log.Fatalf("Supported timestamp types: %v", inactive.SupportedTimestamps())
			}
		}
		inactive.SetImmediateMode(true)
		if handle, err = inactive.Activate(); err != nil {
			log.Fatal("PCAP Activate error:", err)
		}
		defer handle.Close()
		if len(flag.Args()) > 0 {
			bpffilter := strings.Join(flag.Args(), " ")
			fmt.Fprintf(os.Stderr, "Using BPF filter %q\n", bpffilter)
			if err = handle.SetBPFFilter(bpffilter); err != nil {
				log.Fatal("BPF filter error:", err)
			}
		}
	}

	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
	for packet := range packetSource.Packets() {
		if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer != nil {
			if tcpLayer.(*layers.TCP).DstPort != 80 {
				continue
			}
			if tcpLayer.(*layers.TCP).SYN || tcpLayer.(*layers.TCP).RST {
				continue
			}
			data := string(tcpLayer.(*layers.TCP).LayerPayload())
			if !strings.HasPrefix(data, "GET") {
				continue
			}
			fmt.Println("I got GET packet!")
			ethLayer := packet.Layer(layers.LayerTypeEthernet)
			eth := layers.Ethernet{
				SrcMAC:       ethLayer.(*layers.Ethernet).DstMAC,
				DstMAC:       ethLayer.(*layers.Ethernet).SrcMAC,
				EthernetType: layers.EthernetTypeIPv4,
			}
			ipv4Layer := packet.Layer(layers.LayerTypeIPv4)
			ipv4 := layers.IPv4{
				Version:  ipv4Layer.(*layers.IPv4).Version,
				SrcIP:    ipv4Layer.(*layers.IPv4).DstIP,
				DstIP:    ipv4Layer.(*layers.IPv4).SrcIP,
				TTL:      77,
				Id:       ipv4Layer.(*layers.IPv4).Id,
				Protocol: layers.IPProtocolTCP,
			}
			tcp := layers.TCP{
				SrcPort: tcpLayer.(*layers.TCP).DstPort,
				DstPort: tcpLayer.(*layers.TCP).SrcPort,
				PSH:     true,
				ACK:     true,
				FIN:     true,
				Seq:     tcpLayer.(*layers.TCP).Ack,
				Ack:     tcpLayer.(*layers.TCP).Seq + uint32(len(data)),
				Window:  0,
			}
			tcp.SetNetworkLayerForChecksum(&ipv4)
			data =
				`HTTP/1.1 200 OK
Server: nginx
Date: Tue, 26 Jan 2016 13:09:19 GMT
Content-Type: text/plain;charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
Cache-Control: no-store
Pragrma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Content-Length: 7

Stupid!`

//.........这里部分代码省略.........

// AssembleWithTimestamp reassembles the given TCP packet into its appropriate
// stream.
//
// The timestamp passed in must be the timestamp the packet was seen. For
// packets read off the wire, time.Now() should be fine. For packets read from
// PCAP files, CaptureInfo.Timestamp should be passed in. This timestamp will
// affect which streams are flushed by a call to FlushOlderThan.
//
// Each Assemble call results in, in order:
//
//    zero or one calls to StreamFactory.New, creating a stream
//    zero or one calls to Reassembled on a single stream
//    zero or one calls to ReassemblyComplete on the same stream
func (a *Assembler) AssembleWithTimestamp(netFlow gopacket.Flow, t *layers.TCP, timestamp time.Time) {
	// Ignore empty TCP packets
	if !t.SYN && !t.FIN && !t.RST && len(t.LayerPayload()) == 0 {
		return
	}

	a.ret = a.ret[:0]
	key := key{netFlow, t.TransportFlow()}
	var conn *connection
	// This for loop handles a race condition where a connection will close,
	// lock the connection pool, and remove itself, but before it locked the
	// connection pool it's returned to another Assemble statement.  This should
	// loop 0-1 times for the VAST majority of cases.
	for {
		conn = a.connPool.getConnection(
			key, !t.SYN && len(t.LayerPayload()) == 0, timestamp)
		if conn == nil {
			if *debugLog {
				log.Printf("%v got empty packet on otherwise empty connection", key)
			}
			return
		}
		conn.mu.Lock()
		if !conn.closed {
			break
		}
		conn.mu.Unlock()
	}
	if conn.lastSeen.Before(timestamp) {
		conn.lastSeen = timestamp
	}
	seq, bytes := Sequence(t.Seq), t.Payload

	if conn.nextSeq == invalidSequence {
		// Handling the first packet we've seen on the stream.
		skip := 0
		if !t.SYN {
			// don't add 1 since we're just going to assume the sequence number
			// without the SYN packet.
			// stream was picked up somewhere in the middle, so indicate that we
			// don't know how many packets came before it.
			conn.nextSeq = seq.Add(len(bytes))
			skip = -1
		} else {
			// for SYN packets, also increment the sequence number by 1
			conn.nextSeq = seq.Add(len(bytes) + 1)
		}
		a.ret = append(a.ret, tcpassembly.Reassembly{
			Bytes: bytes,
			Skip:  skip,
			Start: t.SYN,
			Seen:  timestamp,
		})
		a.insertIntoConn(t, conn, timestamp)
	} else if diff := conn.nextSeq.Difference(seq); diff > 0 {
		a.insertIntoConn(t, conn, timestamp)
	} else {
		bytes, conn.nextSeq = byteSpan(conn.nextSeq, seq, bytes)
		a.ret = append(a.ret, tcpassembly.Reassembly{
			Bytes: bytes,
			Skip:  0,
			End:   t.RST || t.FIN,
			Seen:  timestamp,
		})
	}
	if len(a.ret) > 0 {
		a.sendToConnection(conn)
	}
	conn.mu.Unlock()
}

func (vnet *VNET) handleTCP(pkt *Packet, now time.Time) {
	// fmt.Printf("TCP: %08x %s\n", pkt.Flags, pkt.String())

	defer pkt.Release()

	var err error

	if bytes.Equal(pkt.Eth.DstMAC, layers.EthernetBroadcast[:]) {
		// ignore
		return
	}

	if pkt.DstHost == nil {
		// ignore
		return
	}
	if !pkt.DstHost.Up {
		log.Printf("destination is down: %s", pkt.DstHost.Name)
		// ignore
		return
	}

	var (
		srcIP   net.IP
		dstIP   net.IP
		srcPort = uint16(pkt.TCP.SrcPort)
		dstPort = uint16(pkt.TCP.DstPort)
	)

	if pkt.IPv4 != nil {
		srcIP = CloneIP(pkt.IPv4.SrcIP.To16())
		dstIP = CloneIP(pkt.IPv4.DstIP.To16())
	} else if pkt.IPv6 != nil {
		srcIP = CloneIP(pkt.IPv6.SrcIP.To16())
		dstIP = CloneIP(pkt.IPv6.DstIP.To16())
	} else {
		log.Printf("invalid protocol")
		// ignore
		return
	}

	route := vnet.routes.GetTable().Lookup(
		protocols.TCP,
		srcIP, dstIP, srcPort, dstPort)

	if route == nil {
		rule, found := vnet.rules.GetTable().Lookup(protocols.TCP, pkt.DstHost.ID, dstPort)
		if !found {
			log.Printf("no rule")
			// ignore
			return
		}

		var (
			ruleDstIP   = rule.DstIP
			ruleDstPort = rule.DstPort
			hostIP      net.IP
			hostPort    uint16
		)

		if ruleDstIP != nil {
			hostIP = dstIP
			hostPort, err = vnet.ports.Allocate(pkt.DstHost.ID, protocols.TCP, 0)
			if err != nil {
				// ignore
				log.Printf("TCP/error: %s", err)
				return
			}

			var r routes.Route
			r.Protocol = protocols.TCP
			r.HostID = pkt.DstHost.ID
			r.SetInboundSource(hostIP, hostPort)
			r.SetInboundDestination(vnet.system.GatewayIPv4(), vnet.proxy.TCPPort)
			r.SetOutboundDestination(ruleDstIP, rule.DstPort)
			route, err = vnet.routes.AddRoute(&r)
			if err != nil {
				// ignore
				log.Printf("TCP/error: %s", err)
				return
			}

			ruleDstIP = vnet.system.GatewayIPv4()
			ruleDstPort = vnet.proxy.TCPPort
		}

		if ruleDstIP == nil {
			gateway := vnet.hosts.GetTable().LookupByName("gateway")
			if gateway == nil || !gateway.Up {
				log.Printf("no gateway")
				// ignore
				return
			}

			if dstIP.To4() != nil {
				if len(gateway.IPv4Addrs) > 0 {
					ruleDstIP = gateway.IPv4Addrs[0]
				}
			} else {
				if len(gateway.IPv6Addrs) > 0 {
//.........这里部分代码省略.........

// AssembleWithTimestamp reassembles the given TCP packet into its appropriate
// stream.
//
// The timestamp passed in must be the timestamp the packet was seen.
// For packets read off the wire, time.Now() should be fine.  For packets read
// from PCAP files, CaptureInfo.Timestamp should be passed in.  This timestamp
// will affect which streams are flushed by a call to FlushOlderThan.
//
// Each Assemble call results in, in order:
//
//    zero or one calls to StreamFactory.New, creating a stream
//    zero or one calls to Reassembled on a single stream
//    zero or one calls to ReassemblyComplete on the same stream
func (a *Assembler) AssembleWithTimestamp(netFlow gopacket.Flow, t *layers.TCP, timestamp time.Time) {
	// Ignore empty TCP packets
	if !t.SYN && !t.FIN && !t.RST && len(t.LayerPayload()) == 0 {
		if *debugLog {
			log.Println("ignoring useless packet")
		}
		return
	}

	a.ret = a.ret[:0]
	key := key{netFlow, t.TransportFlow()}
	var conn *connection
	// This for loop handles a race condition where a connection will close, lock
	// the connection pool, and remove itself, but before it locked the connection
	// pool it's returned to another Assemble statement.  This should loop 0-1
	// times for the VAST majority of cases.
	for {
		conn = a.connPool.getConnection(
			key, !t.SYN && len(t.LayerPayload()) == 0, timestamp)
		if conn == nil {
			if *debugLog {
				log.Printf("%v got empty packet on otherwise empty connection", key)
			}
			return
		}
		conn.mu.Lock()
		if !conn.closed {
			break
		}
		conn.mu.Unlock()
	}
	if conn.lastSeen.Before(timestamp) {
		conn.lastSeen = timestamp
	}
	seq, bytes := Sequence(t.Seq), t.Payload
	if conn.nextSeq == invalidSequence {
		if t.SYN {
			if *debugLog {
				log.Printf("%v saw first SYN packet, returning immediately, seq=%v", key, seq)
			}
			a.ret = append(a.ret, Reassembly{
				Bytes: bytes,
				Skip:  0,
				Start: true,
				Seen:  timestamp,
			})
			conn.nextSeq = seq.Add(len(bytes) + 1)
		} else {
			if *debugLog {
				log.Printf("%v waiting for start, storing into connection", key)
			}
			a.insertIntoConn(t, conn, timestamp)
		}
	} else if diff := conn.nextSeq.Difference(seq); diff > 0 {
		if *debugLog {
			log.Printf("%v gap in sequence numbers (%v, %v) diff %v, storing into connection", key, conn.nextSeq, seq, diff)
		}
		a.insertIntoConn(t, conn, timestamp)
	} else {
		bytes, conn.nextSeq = byteSpan(conn.nextSeq, seq, bytes)
		if *debugLog {
			log.Printf("%v found contiguous data (%v, %v), returning immediately", key, seq, conn.nextSeq)
		}
		a.ret = append(a.ret, Reassembly{
			Bytes: bytes,
			Skip:  0,
			End:   t.RST || t.FIN,
			Seen:  timestamp,
		})
	}
	if len(a.ret) > 0 {
		a.sendToConnection(conn)
	}
	conn.mu.Unlock()
}

// scan scans the dst IP address of this scanner.
func (s *scanner) scan() error {
	// First off, get the MAC address we should be sending packets to.
	hwaddr, err := s.getHwAddr()
	if err != nil {
		return err
	}
	// Construct all the network layers we need.
	eth := layers.Ethernet{
		SrcMAC:       s.iface.HardwareAddr,
		DstMAC:       hwaddr,
		EthernetType: layers.EthernetTypeIPv4,
	}
	ip4 := layers.IPv4{
		SrcIP:    s.src,
		DstIP:    s.dst,
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SrcPort: 54321,
		DstPort: 0, // will be incremented during the scan
		SYN:     true,
	}
	tcp.SetNetworkLayerForChecksum(&ip4)

	// Create the flow we expect returning packets to have, so we can check
	// against it and discard useless packets.
	ipFlow := gopacket.NewFlow(layers.EndpointIPv4, s.dst, s.src)
	start := time.Now()
	for {
		// Send one packet per loop iteration until we've sent packets
		// to all of ports [1, 65535].
		if tcp.DstPort < 65535 {
			start = time.Now()
			tcp.DstPort++
			if err := s.send(&eth, &ip4, &tcp); err != nil {
				log.Printf("error sending to port %v: %v", tcp.DstPort, err)
			}
		}
		// Time out 5 seconds after the last packet we sent.
		if time.Since(start) > time.Second*5 {
			log.Printf("timed out for %v, assuming we've seen all we can", s.dst)
			return nil
		}

		// Read in the next packet.
		data, _, err := s.handle.ReadPacketData()
		if err == pcap.NextErrorTimeoutExpired {
			continue
		} else if err != nil {
			log.Printf("error reading packet: %v", err)
			continue
		}

		// Parse the packet.  We'd use DecodingLayerParser here if we
		// wanted to be really fast.
		packet := gopacket.NewPacket(data, layers.LayerTypeEthernet, gopacket.NoCopy)

		// Find the packets we care about, and print out logging
		// information about them.  All others are ignored.
		if net := packet.NetworkLayer(); net == nil {
			// log.Printf("packet has no network layer")
		} else if net.NetworkFlow() != ipFlow {
			// log.Printf("packet does not match our ip src/dst")
		} else if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer == nil {
			// log.Printf("packet has not tcp layer")
		} else if tcp, ok := tcpLayer.(*layers.TCP); !ok {
			// We panic here because this is guaranteed to never
			// happen.
			panic("tcp layer is not tcp layer :-/")
		} else if tcp.DstPort != 54321 {
			// log.Printf("dst port %v does not match", tcp.DstPort)
		} else if tcp.RST {
			log.Printf("  port %v closed", tcp.SrcPort)
		} else if tcp.SYN && tcp.ACK {
			log.Printf("  port %v open", tcp.SrcPort)
		} else {
			// log.Printf("ignoring useless packet")
		}
	}
}

func main() {
	defer util.Run()()

	var eth layers.Ethernet
	var dot1q layers.Dot1Q
	var ip4 layers.IPv4
	var tcp layers.TCP
	var payload gopacket.Payload

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	hijackSeq := r.Uint32()

	decoded := make([]gopacket.LayerType, 0, 4)

	streamInjector := attack.TCPStreamInjector{}
	err := streamInjector.Init("0.0.0.0")
	if err != nil {
		panic(err)
	}

	handle, err := pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever)
	if err != nil {
		log.Fatal("error opening pcap handle: ", err)
	}
	if err := handle.SetBPFFilter(*filter); err != nil {
		log.Fatal("error setting BPF filter: ", err)
	}
	parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet,
		&eth, &dot1q, &ip4, &tcp, &payload)

	log.Print("collecting packets...\n")
	for {
		data, ci, err := handle.ZeroCopyReadPacketData()
		if err != nil {
			log.Printf("error getting packet: %v %s", err, ci)
			continue
		}
		err = parser.DecodeLayers(data, &decoded)
		if err != nil {
			log.Printf("error decoding packet: %v", err)
			continue
		}

		// craft a response to the client
		// here we reuse the client's header
		// by swapping addrs and ports

		// swap ip addrs
		srcip := ip4.SrcIP
		ip4.SrcIP = ip4.DstIP
		ip4.DstIP = srcip

		// swap ports
		srcport := tcp.SrcPort
		tcp.SrcPort = tcp.DstPort
		tcp.DstPort = srcport

		// empty payload for SYN/ACK handshake completion
		streamInjector.Payload = []byte("")
		seq := tcp.Seq
		tcp.Seq = hijackSeq
		tcp.Ack = uint32(tcpassembly.Sequence(seq).Add(1))
		tcp.ACK = true
		tcp.SYN = true
		tcp.RST = false

		err = streamInjector.SetIPLayer(ip4)
		if err != nil {
			panic(err)
		}
		streamInjector.SetTCPLayer(tcp)
		err = streamInjector.Write()
		if err != nil {
			panic(err)
		}
		log.Print("SYN/ACK packet sent!\n")

		// send rediction payload
		redirect := []byte("HTTP/1.1 307 Temporary Redirect\r\nLocation: http://127.0.0.1/?\r\n\r\n")
		streamInjector.Payload = redirect
		tcp.PSH = true
		tcp.SYN = false
		tcp.ACK = true
		tcp.Ack = uint32(tcpassembly.Sequence(seq).Add(1))
		tcp.Seq = uint32(tcpassembly.Sequence(hijackSeq).Add(1))

		err = streamInjector.SetIPLayer(ip4)
		if err != nil {
			panic(err)
		}
		streamInjector.SetTCPLayer(tcp)
		err = streamInjector.Write()
		if err != nil {
			panic(err)
		}
		log.Print("redirect packet sent!\n")

		// send FIN
		streamInjector.Payload = []byte("")
		tcp.FIN = true
//.........这里部分代码省略.........

func (i *Filter) decodePackets() {
	var eth layers.Ethernet
	var ip layers.IPv4
	var ipv6 layers.IPv6
	var tcp layers.TCP
	var udp layers.UDP
	var payload gopacket.Payload
	anomalyTest := make(chan *Pan)
	alertChan := make(chan *AlertMessage)
	panClose := make(chan *PanCtl)

	//_, IPNet, err := net.ParseCIDR("10.240.0.0/16")
	_, IPNet, err := net.ParseCIDR(i.options.FilterIpCIDR)
	if err != nil {
		log.Errorf("Error parsing CIDR: %#v", err)
		i.Stop()
	}

	decodedLen := 6
	parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet, &eth, &ip, &ipv6, &tcp, &udp, &payload)
	decoded := make([]gopacket.LayerType, 0, decodedLen)

	// Initialize wherefore goroutines
	piChan := PanopticonInfo()
	/*
		for at := 0; at < 10; at++ {
		}
	*/
	go i.AnomalyTester(anomalyTest, piChan, alertChan)
	go i.AlertSlack(alertChan)
	go i.PanRemover(panClose)

	for {
		select {
		case <-i.stopDecodeChan:
			return
		case timedRawPacket := <-i.decodePacketChan:
			newPayload := new(gopacket.Payload)
			payload = *newPayload
			err := parser.DecodeLayers(timedRawPacket.RawPacket, &decoded)
			if err != nil {
				continue
			}

			flow := types.NewTcpIpFlowFromFlows(ip.NetworkFlow(), tcp.TransportFlow())
			dcopy := make([]gopacket.LayerType, decodedLen, decodedLen)
			if dc := copy(dcopy, decoded); dc <= 0 {
				log.Errorf("Copy of decoded layers failed: %d", dc)
				continue
			}
			packetManifest := types.PacketManifest{
				Timestamp:     timedRawPacket.Timestamp,
				Flow:          flow,
				RawPacket:     timedRawPacket.RawPacket,
				DecodedLayers: dcopy,
				Eth:           eth,
				IP:            ip,
				IPv4:          ip,
				IPv6:          ipv6,
				TCP:           tcp,
				UDP:           udp,
				Payload:       payload,
			}

			//Short circut to only watch traffic heading in one direction
			//if FilterExternal(&packetManifest) == nil {
			if i.options.FilterSrc {
				if i.options.FilterBool && IPNet.Contains(packetManifest.IP.SrcIP) {
					continue
				}
			}

			if i.options.FilterDst {
				if i.options.FilterBool && IPNet.Contains(packetManifest.IP.DstIP) {
					continue
				}
			}

			//Pass packet manifest to the PM-Monitor function
			//TODO: Improve the flow around packet processing from the sniffer/splitter
			i.PMMonitor(&packetManifest, anomalyTest, panClose)

		}
	}
}

// NewTcpIpFlowFromLayers given IPv4 and TCP layers it returns a TcpIpFlow
func NewTcpIpFlowFromLayers(ipLayer layers.IPv4, tcpLayer layers.TCP) *TcpIpFlow {
	return &TcpIpFlow{
		ipFlow:  ipLayer.NetworkFlow(),
		tcpFlow: tcpLayer.TransportFlow(),
	}
}